The present invention relates to a computer system run on a primary site and a secondary site switching technique for when a failure takes place.
There are many systems running in an information-driven society that provide services via the Internet, for example, a ticket reservation system and a network banking system. Many of such systems has two sites (a primary site and a secondary site) and keeps the secondary site on hot standby, so that switching is made quickly to the secondary site in case the primary site suffers a failure making the failure to stop the system only for a brief period of time (see JP 2002-312189 A, for example).
The Internet has a DNS server for name resolution processing, which gives an IP address of a server accessed by a client. A cache of DNS information that gives the IP address is set on Internet, to thereby lighten the load of the DNS server and shorten the name resolution processing time (for example, see Request for Comments: 1034, “Domain Names—Concepts and Facilities”, http://www.ietf.org/rfc/rfc1034.txt).